--     you called yesterday evening?

---My sister. Why?

A．Who it is that

B．Who is it that

C．Who was it that

D．Who it was that

在下面哪种情况下，使用万用表测量时、表棒不分正负极（）

A.测量交流电压；

B.测量直流电压；

C.测量直流电流；

D.测量电阻。